Had kinda the same issue. I tried viewing an jpg attachment and I wasn't able to view it. To do further tests, I took a picture and emailed it to myself on the tab and had the same results. I also noticed the gallery function lagged a bit. After deleting all the photos from the gallery, I noticed when I clicked on gallery that although there weren't any photos, there seem to be a enlarged/blurry image of one of the images that I deleted. Hope they figure out what's causing this issue...viewing photos is pretty basic and shouldn't be so troublesome. I worked around this problem by installing quickpic from the market and set it as my default viewer. Now I can view email attachments without any problems.
One other thing...I'm coming from the HTC Evo android overlay. It might be because I'm still new at it but the Samsung Tab overlay doesn't seem as logical in the layout (menus, etc.). Although, samsung users might say the same for the Evo.